1. Population Sizes

2. What is a Population? • All the members of a species in an area

3. Describe to a partner all the ways you think a population can change.

4. Populations can change in a number of ways: • Births • Deaths • Immigration- members of a species coming into or joining a population • Emigration- members of a species leaving a population

5. Birth and Death Rates • Birth rate- the number of births in a population in a certain amount of time • Death rate- the number of deaths in a population in a certain amount of time Natural Population = br (birth rate) – dr (death rate) Growth

6. Natural Population = br (birth rate) – dr (death rate) Growth Practice Problem: At Banner Desert Hospitals in Arizona, 350 babies are born a year, and 200 people pass away. What is the natural population growth of Arizona?

7. Natural Population = br (birth rate) – dr (death rate) Growth • If the birth rate is greater than the death rate, the population is ___________. • If the birth rate is less than the death rate, the population is ___________.

8. Natural Population = br (birth rate) – dr (death rate) Growth • If the birth rate is greater than the death rate, the population is _increasing_. • If the birth rate is less than the death rate, the population is _decreasing_.

9. Increasing and Decreasing Populations Increasing Population Graph Decreasing Population Graph

10. Limiting Factors • The size of a population is limited by specific factors (biotic and abiotic) in the environment. • These cause a population to stop growing.

11. Limiting Factors Main 4 Limiting Factors: • Food • Water • Shelter • Space Other factors: • Disease • Natural disasters • Predation • Invasive species • Temperature *The most effective limiting factors for plants and animals may be different.

12. Population Density • the average number of organisms in a specific area. • Space is the biggest factor contributing to population density.

13. Calculating Population Density Number of Species in a Population The area Population Density = • Your answer is going to be a decimal. • The closer the decimal is to 1, the greater the density- or more crowded it is. • The closer the decimal is to 0, the less the density- or more spacious it is.

14. Population Density Practice Problem • If the size of the classroom is 10 feet wide and 20 feet long, and there are 30 students in the classroom, what is the population density of the classroom? STEPS: • Find the area (A= l*w) • Divide the population number by the area (or plug into the equation)

15. Answer Population 30 students Density = 200 sq ft. = 0.15 • Is this PD crowded, or spacious?

16. Carrying Capacity K • the largest population that an area can support • Carry capacity is represented by ‘k’ in mathematical equations.

17. Exit Slip • What are the 4 main limiting factors of an environment? • Complete this natural growth rate problem: If 50 children are born in Omaha, Nebraska, and 20 elderly people pass away in one year, what is the population growth?

18. Oh Deer! Activity 4 groups of students: • Deers- looking for a limiting factor • Food- will cover stomach with hands • Shelter- will put hands over head like a house • Water- will put hands over mouth

19. Directions • Students will be numbered off into groups • Food, shelter, and water will be in the “habitat” • Deers will line up on the line. • Deers must decide on the line which resource they are looking for. YOU CANNOT CHANGE YOUR RESOURCE AFTER YOU HAVE LEFT THE LINE!! • When I say “GO!” Food, shelter, and water will create the signs of their role in the habitat and the deers will run to find the chosen resource. • Deers that do not find a resource die (go to side) • Resources that are chosen become deer for the next round